Neotropical Ichthyology, 7(3):289-293, 2009 Copyright © 2009 Sociedade Brasileira de Ictiologia New species of Cetopsidium (Siluriformes: Cetopsidae: Cetopsinae) from the upper rio Branco system in Guyana Richard P. Vari 1 and Carl J. Ferraris Jr.2 Cetopsidium soniae, new species, is described from the Takutu River basin of southwestern Guyana, within the upper portions of the rio Branco of the Amazon basin. The new species differs from its congeners in details of pigmentation, the length of the pelvic fin, the form of the first rays of the dorsal and pectoral fins in mature males, the relative alignment of the dorsal and ventral profiles of the postdorsal portion of the body, the position of the anus, and the depth of the body. DNA barcodes were generated for the holotype and paratype. An examination of other samples of Cetopsidium from the rio Branco system extends the range of C. pemon into the Ireng River system of Guyana. Cetopsidium soniae, espécie nova, é descrita da bacia do rio Takutu, sudoeste da Guiana, na porção superior do rio Branco, bacia Amazônica. A nova espécie difere das demais espécies do gênero em detalhes de pigmentação, pelo comprimento da nadadeira pélvica, na forma dos primeiros raios das nadadeiras dorsal e peitoral em machos maduros, no relativo alinhamento dos perfis dorsal e ventral da região pós-dorsal do corpo, na posição do ânus, e na altura do corpo. Códigos de barra de DNA foram gerados para o holótipo e parátipo. O exame de outras amostras de Cetopsidium do sistema do rio Branco estende a distribuição de C. pemon até o sistema do rio Ireng na Guiana. Key words: Taxonomy, New Catfish, Takutu River basin. Introduction access or thoroughly sample (Vari & Malabarba, 1998) and as would be expected, collecting efforts in those settings The Neotropical catfishes of the subfamily Cetopsinae continue to yield numerous species previously unknown to have a broad distribution throughout much of South America science. Examination of a sample of Cetopsidium from the to both sides of the cordilleras of the Andes. Recent studies Takutu River system in the Rupununi region of southwestern of the species-level taxonomy of the Cetopsinae (Oliveira et Guyana revealed a previously unknown species of the genus al., 2001; Vari et al., 2003, 2005) resulted in the description of that we describe herein. 19 new species for a total of 37 species in the subfamily. That notable degree of previously undetected species diversity in Material and Methods conjunction with the major areas within the range of the Cetopsinae from which samples of the subfamily remain sparse Institutional abbreviations are ANSP, Academy of Natural or unknown makes it very likely that the species level Sciences, Philadelphia; CSBD, Centre for the Study of Biological understanding of the Cetopsinae remains far from complete. Diversity, University of Guyana, Georgetown; MHNG, Muséum Exemplifying this situation is the genus Cetopsidium Vari et d’histoire naturelle, Geneva; and USNM, National Museum of al., 2005, that underwent an increase from two to six recognized Natural History, Smithsonian Institution, Washington, D.C. species in the last six years (Vari et al., 2003, 2005). Species of All measurements are straight-line distances between Cetopsidium are of relatively small body sizes and typically points with head length (HL) measured from the snout to the inhabit streams and smaller rivers in localities scattered across end of the fleshy gill cover. Interorbital width was taken as central and northern cis-Andean South America (Vari et al., the shortest distance between the orbits, but is difficult to 2005, fig. 2). Such habitats are by their nature often difficult to measure unambiguously. Size of examined specimens is 1Division of Fishes, Department of Vertebrate Zoology, MRC-159, National Museum of Natural History, PO Box 37012, Smithsonian Institution, Washington, D.C. 20013-7012. [email protected] 22944 NE Couch Street, Portland, Oregon, 97232, U.S.A., and Research Associate, Department of Vertebrate Zoology, MRC-159, National Museum of Natural History, PO Box 37012, Smithsonian Institution, Washington, D.C. 20013-7012, U.S.A. [email protected] 289 290 New species of Cetopsidium from the upper rio Branco system in Guyana reported as standard length (SL). Radioopacity of the limited and reaching to or slightly beyond the anterior limit of the available sample of the new species because of the original vent in C. ferreirai Vari, Ferraris & de Pinna, 2005, C. morenoi fixative made it impossible to determine the number of preanal, (Fernández-Yépez, 1972), C. orientale (Vari, Ferraris & Keith, precaudal, caudal, and total vertebrae. Counts of fin rays were 2003), and C. pemon Vari, Ferraris & de Pinna, 2005, the position from whole specimens. Because of the condition of the sample, of the vent (proximate to the base of the anterior most anal-fin we do not distinguish unbranched from branched rays other ray versus distinctly anterior to that location in C. roae Vari, than in the case of the pelvic fin. The dorsal spinelet is not Ferraris & de Pinna, 2005), the form of the first rays of the included in the count of rays for that fin. Specimens were dorsal and pectoral fins (with distal filaments present in males sexed based on their possession of the sexually dimorphic versus without such sexually-dimorphic filaments in C. features that are present in congeners. The range of values ferreirai), the orientation of the dorsal and ventral profiles of for meristic and morphometric features in the species is the postdorsal portion of the body (converging posteriorly presented first, followed by the value for the holotype in versus running in parallel in C. orientale), the distribution of square brackets. Tissue samples from the holotype and dark pigmentation on the body (with pigmentation distributed paratypes were preserved in 80% ethanol and stored at -20°C. across dorsal and lateral surfaces of body versus limited to Total genomic DNA was extracted with the DNeasy Tissue middorsal region in C. ferreirai), the degree of dark Kit (Qiagen) following the instructions of the manufacturer. pigmentation on the ventral surface of the lower jaw (with The PCR amplifications of the 648-bp region of the limited or no pigmentation versus with broad band of cytochrome c oxidase I (COI) mitochondrial gene required for pigmentation in C. orientale), the form of the pigmentation DNA barcodes were carried out using the Taq PCR Core Kit on the head and body (chromatophores large and stellate versus (Qiagen). The primers used were: Fish-F1 5’-TCA ACC AAC small and round in C. minutum and C. pemon), the extent of the CAC AAA GAC ATT GGC AC-3’ and Fish-R1 5’-TAG ACT pigmentation on the dorsal fin (without any pigmentation or at TCT GGG TGG CCA AAG AAT CA-3’. The amplifications most several small dark basal spots versus with distinct were performed in a total volume of 50 µl, containing 5 µl of semicircular dark spot basally in C. morenoi, C. orientale, and 10x reaction buffer, 1 µl of dNTP mix at 10 µM each, 1 µl of C. pemon), the body depth (0.17-0.18 versus 0.14-0.15 of SL in each primer at 10 µM, 0.2 µl of Taq DNA Polymerase equivalent C. roae), and the form of the head in lateral view (triangular to 1 unit of Polymerase per tube, and 1 µl of DNA. Cycles of overall but relatively deep posteriorly versus more acutely amplification were programmed with the following the profile: triangular in C. minutum [see Vari et al., 2005, fig. 3]). (1) 3 min. at 94°C (initial denaturing), (2) 35 sec. at 94°C, (3) 30 sec. at 54°C, (4) 50 sec. at 72°C, and (5) 5 min. at 72°C (final Description. Body moderately robust, somewhat compressed elongation). Steps 2 to 4 were repeated 39 times. PCR products anteriorly and becomes progressively distinctly compressed were purified with the High Pure PCR Product Purification Kit posteriorly. Body depth at dorsal-fin origin approximately 0.17- (Roche). Sequencing reactions were performed with the Big 0.18 [0.17] of SL, and approximately equal to distance from Dye Terminator Cycle Sequencing Ready Reaction 3.1 Kit anterior margin of eye to rear of head. Lateral line on body (Applied Biosystems) following instructions of the unbranched, midlateral, incomplete, and extends from vertical manufacturer, and were loaded on an automatic sequencer 3100- through pectoral-fin base posteriorly to point within region Avant Genetic Analyzer (Applied Biosystems, Perkin-Elmer). from above middle of anal-fin base to slightly anterior to vertical through base of posterior most anal-fin ray. Dorsal profile of Results body straight from nape to dorsal-fin origin, slightly posteroventrally-aligned along base of dorsal fin and then straight from base of last dorsal-fin ray to caudal-fin base. Cetopsidium soniae, new species Ventral profile of body slightly convex along abdomen, Fig. 1 approximately straight and slightly converging posteriorly towards dorsal profile of body along anal-fin base. Caudal- Holotype. CSBD F1665; formerly MHNG 2652.014, in part, 30.9 peduncle depth greater than caudal-peduncle length. mm, male, Guyana, Central Rupununi (Region 9), main channel of Head relatively deep posteriorly, with lateral profile Manari River, Takutu River basin, along road between Lethem and triangular overall but with bluntly pointed snout. Dorsal profile Annai, near Lethem, 3°26.590’N 59°44.578’W, altitude 329 m, B. of head in male straight to slightly convex anteriorly, then Allocock, G. King, J. I. Montoya-Burgos, R. Covain, A. Fort & R. straight to vertical located one orbital diameter posterior of Daniels, 29 Oct 2004. rear margin of orbit, and finally broadly convex from that point Paratype.